The aims of this research are: (1) to evaluate the effects of group home placement on drug use of delinquent youths, and (2) to analyze the relationship between drug use and various behavioral influences. Subjects for the study will be 100 treatment youths from 14 Kansas group homes, and a comparison group of youths who were named by the treatment youths as their friend at the time of placement. A self-report questionnaire will be used to measure the drug use of treatment subjects (a) during the year and the month prior to placement, (b) each month during treatment, and (c) once each month for 6 months following treatment. Data on the drug use of comparison youths will be collected on the same schedule. The effects of the group home will be examined by group comparisons as well as comparisons across pre, during and post treatment conditions. Characteristics of the group home families, as well as of the natural families of the friend sample, will be measured by youth and parent questionnaires. The group-home families will be periodically measured through direct behavioral observation; the natural families of 30 friends of the group-home youths will also be observed directly. Questionnaire and direct behavioral measures will emphasize parental adult reinforcing value and social teaching. Questionnaire data will also be collected concerning the experienced or anticipated differential consequences for drug use which are provided by peers or school teachers, or which are personal (physical or psychological) in nature. All treatment youths will also be asked to name their best friend in the group-home once each month in order to see if entering youths select friends that are similar to themselves in drug use or come to match the drug use of their friends. The data on parental adult influences, differential consequences, and peer drug use will be used in correlational analyses, with subjects' drug use as the primary outcome variable.